FDA Adds Strongest Warning to Sarepta’s Duchenne Gene Therapy Following Two Patient Deaths

The U.S. Food and Drug Administration (FDA) announced on Friday that it will add its most severe safety warning — a boxed warning — to Sarepta Therapeutics’ gene therapy Elevidys, following two reported patient deaths linked to the treatment earlier this year.

The FDA’s decision marks a significant development in the ongoing scrutiny surrounding the first-ever approved gene therapy for Duchenne muscular dystrophy (DMD), a devastating genetic disorder that causes progressive muscle degeneration primarily in boys and young men.

Elevidys, which is delivered via a single infusion, has faced controversy since March 2025, when the first of two teenage boys died shortly after receiving the therapy. A second death was reported in June, prompting the FDA to temporarily suspend shipments of the drug pending review.

Although shipments resumed following outcry from patient advocacy groups and political figures, the agency’s latest move underscores the serious risks associated with the therapy.

According to the FDA, the deaths were likely caused by acute liver failure, an adverse reaction that had been previously documented but not fully emphasized in Elevidys’ initial labeling.

A boxed warning—commonly known as a “black box warning”—is the FDA’s most prominent safety alert. It signals that a drug carries a potentially life-threatening risk and must include clear language to inform healthcare providers and patients of that danger.

In the case of Elevidys, the new boxed warning will highlight the risk of severe and potentially fatal liver toxicity.

The FDA also introduced new usage limitations, restricting Elevidys to:

• Patients aged 4 years and older, and
• Those who retain the ability to walk.

Previously, the therapy could be used in patients with more advanced disease who had lost mobility — a group now excluded from approved treatment parameters.

The updated labeling will also call for weekly liver function monitoring for the first three months post-infusion and emphasize the need for close medical supervision during the recovery period.

About Elevidys and Duchenne Muscular Dystrophy

Elevidys, developed by Sarepta Therapeutics, is a gene therapy designed to deliver a shortened version of the dystrophin gene — the protein that is missing or defective in patients with DMD.

Duchenne muscular dystrophy is one of the most severe inherited neuromuscular diseases, typically diagnosed in early childhood. Most patients lose the ability to walk by their early teens, and life expectancy often does not extend beyond the third decade of life.

Elevidys was initially hailed as a groundbreaking treatment when it received FDA approval in 2023, marking a milestone in the fight against a disease for which no cure exists. However, the recent fatalities have raised difficult questions about risk versus reward in gene therapy medicine.

Sarepta’s Response and Financial Impact

Sarepta Therapeutics, headquartered in Cambridge, Massachusetts, has faced intense scrutiny following the deaths. In July 2025, the company announced it would lay off 500 employees amid regulatory uncertainty and declining investor confidence.

Despite the FDA’s new restrictions, Sarepta’s shares rose 7.7% in trading after Friday’s announcement, as the updated guidelines provided greater regulatory clarity and signaled that the agency is not withdrawing approval of Elevidys altogether.

In a statement, Sarepta said it would “fully cooperate with the FDA” and reaffirmed its commitment to patient safety and continued research.

Balancing Hope and Risk in Gene Therapy

The Elevidys case underscores the ethical and scientific complexities of modern gene therapy. These treatments offer unprecedented potential for life-altering benefits but come with serious and sometimes fatal side effects due to immune reactions or organ toxicity.

While the FDA’s warning is expected to curb some use of the therapy, families of children with Duchenne say the drug remains a critical lifeline — especially for those who have exhausted all other options.

What Patients and Families Should Know

For families considering or currently undergoing Elevidys treatment, medical experts urge vigilance and proactive communication with healthcare providers.

Patients should:

• Ensure frequent liver function testing after infusion.
• Report symptoms such as jaundice, nausea, fatigue, or dark urine immediately.
• Receive care at experienced gene therapy centers equipped for emergency intervention.

Doctors are also being advised to carefully screen candidates and discuss the risks versus benefits in detail before administering the therapy.

The Broader Implications for Gene Therapy Regulation

The FDA’s decision could influence how future gene therapies are evaluated, especially those involving high-risk patient populations. Regulators worldwide may look to this case as an example of balancing innovation with safety oversight.

Despite the tragedies, experts stress that gene therapy remains one of the most promising frontiers in medicine. As regulatory agencies refine safety protocols and companies improve delivery methods, the field continues to evolve toward safer, more effective applications.

The FDA’s addition of a boxed warning to Sarepta’s Elevidys gene therapy serves as both a caution and a reminder of the fragile balance between medical innovation and patient safety.

For the families affected by Duchenne muscular dystrophy, Elevidys still represents hope — but one that must now be approached with heightened vigilance and informed consent.

As investigations continue, the FDA and Sarepta Therapeutics are expected to issue further updates on risk mitigation and patient monitoring protocols in the coming months.